High-speed telephoto objective



SEARCH RDOM SR I Sept. 29, 1959 s. KLEMT EI'AL mca-srm TELEPHOTO OBJECTIVE Fiied July 26, 1957 1%. 3 AGENT" United States Patent 1 O HIGH-SPEED TELEPHOTO OBJECTIVE Giinter Klemt and Heinrich Macher, Krenznach, Rhineland, Germany, assignors to Joe. Schneider & Co.,

Kreuznach, Rhineland, Germany, a company of Germany Application July 26, 1951, Serial No. 674,442

Claims priority, application Germany August 7, 1956 3 Claims. (CI. 88-57) telephoto objective satisfying these desiderata. A more specific object of our invention is to provide an objective system, of the character set forth, maintaining a good correction for all known types of aberration.

A feature of our invention resides in the provision of a telephoto objective of the construction set forth in which the two lensgroups constitute the front and rear halves of a Gaussian dual objective having a front component in the form of a single lens, followed by a compound member cemented from two lenses of opposite refractivity, the rear half of the system consisting of two air-spaced single lenses, the relationships of the refractive powers and of the physical dimensions being such that the focal length of the front half ranges between 85% and 100% of the overall focal length of the system and that the back-focal distance of this front half is less than 65 of the overall focal length.

For the realization of the desired telephoto effect it is furthermore advantageous, according to another feature of the invention, that the air space between the positively refracting front half and the negatively retracting rear half be greater than 0.4 time the total axial length of the system (measured between the outer vertices of its front and rear lenses) but less than 40% of the over all focal length. 7 j

A further feature of the invention, designed to eliminateimage curvature and astigmatism, resides in such a dimensioning of the cemented component of the front half that the ratio of the radii of curvature of its outer surfaces is less than 1.3, the difference between the refractive indices of the cemented lenses being at the same time greater than 0.15.

The invention will be described in greater detail with reference to the accompanying drawing in which Figs. 1 and 2 diagrammatically illustrate two different embodiments.

In Fig. 1 there has been shown a telephoto objective consisting of a front lens group I and a rear lens group II, the two groups consistuting the halves of a Gaussian dual objective. Front group or half I is composed of a positive meniscus L followed by a positively refracting lens L; which is cemented onto a negatively refracting lens L to form a compound meniscus. The rear group or half II, separated from front half I by a diaphragm space d consists of a negative meniscus L and a posi tive meniscus L5, each being in the form of a single lens. The following Table A lists representative numerical 2,906,173 Patented I Sept. 29, 1959 values, based upon an overall focal length f of numerical I value 100, for the radii r to r, and the thicknesses and spacings d to d of lenses L to L along with their refractive indices n and their Abb numbers 1!, all relating to an objective system of aperture ratio 1:4.0 and back-focal distance s=47.1.

In the system of Table A the focal length f of front lens L has the numerical value of 88.6, being thus between and of the overall focal length f=l00, while the back-focal distance S of the front group I amounts to 58.1, being thus less than 65% of focal length f. The ratio r :r of the outer radii of the cemented member L L is less than 1.3 and the difference between the refractive indices n of lenses L and L is 0.20.

In Fig. 2 a modified system according to the invention has been shown in which the lenses of the front group I have been designated L L and L while the lenses of the rear group II bear the designations L and L In the following Table B we have given representative numerical values, based again upon a numerical value of 100 for the overall focal length f of this system, for the radii r to r and for the thicknesses and spacings d to d of the objective shown in Fig. 2, along with the refractive indices n and the Abb numbers 11 thereof, the system having an aperture ratio of 124.0 and a backfocal distance s'=47 1 The focal length f, of the front lens L 98.6, being" thus again between 85% and 100% of the overall focal length. The back-focal distance s amounts to 64.0,

hence is again less than 65% of the overall focal length.

In this system, too, the ratio r :r of the outer radii of the cemented component L '-L is again less than 1.3

and the difierence of the refractive indices of the cemented I lenses is once more greater than 0.15, being 0.16 in the case of lenses L and L We claim:

1. A telephoto objective system comprising a positively refracting front lens group and a negatively refracting rear lens group separated by a large air space, said lens groups constituting respective halves of a Gaussian dual 3. An objective system according to claim 1, having numerical values substantially as given in the following objective, said front group consisting of a single menisousbl shaped positive front lens followed by a cemented negative meniscus composed of lenses of opposite refractivity, 5 n,=+26 37 m said rear group consisting of two air-spaced single lenses, Ll I (11 5.28 1.5182 05.2 said front group having a focal length ranging between =+84A2 12,: M8 Airspace 85% and 100% of the overall focal length of the system L I n=+22.81 I and having a back-focal distance less than 65% of said #:4386152 1'4645 overall focal length, said objective system having an over- 10 a d4= 5.65 1.6645 35.9 all focal length of numerical value 100 and an aperture +1947 10 Diaphragm 8pm ratio of 1:40, the radii r r the thicknesses and spac- L I n'=-14.09 d I 1 ings d d the refractive indices n and the Abb numm3 hers I! of said front lens L said lenses L L of said +8409 d 0,24 Airspace cemented meniscus, and said air-spaced single lenses ,I 204 7215 293 L L having numerical values substantially as given in o'=-7 the following table:

. +24.6 n +27.6 L1 5. 0 d1 5.6 1. 51 1ld 1- 59 61. 0 05.4

55 d 61 Air space +21. 7 n +27. 3 In 7.0 d= 7.7 1. 46 m 1. 49 65.6 v 70.2

--1456. 0 n -117s. 0 TA 5. 0 d4 5.9 1.64 nd 1.67 33.8 v 36.0

15. 3 d 18. 0 Diaphragm space -15. 5 n -13. 2 L. 1. 0 d. 1.2 1.61 7ld 1.63 57.1 v 60.6

. 23 d1 1. 3 Air space -295. 0 ra +88. 0 r. 1. 9 d 2.2 1. 72 1ld 1.73 29.2 v 29.4

2. An objective system according to claim 1, having numerical values substantially as given in the following table:

35 I c 0 References Cited m the file of this patent UNITED STATES PATENTS I 1,791,276 Konig Feb. 3, 1931 44 1-4875 2,169,130 Tronnier et al. Aug.'8, 1939 "5 5,29 1,64" 3,9 2,321,973 Bennett June 15, 1943 d 14 Dig mans m 2,631,497 Schlegel Mar. 17, 1953 n=14.70 p p 2,660,093 Bertele Nov. 24, 1953 2299 1-6134 2,660,095 Cook Nov. 24, 1953 Airs we FOREIGN PATENTS "=49 u 1'7215 I 363,499 France -2..- May 7, 1906 487,271 Germany Dec. 11, 1929 

